Portions of this article were originally published Sept. 27, 2004. It has been updated with more recent information about Abu Musab al-Zarqawi and the events leading up to his death.

The killing of the insurgent leader Abu Musab al-Zarqawi in an airstrike Wednesday brought an end to the career of one of the United States' most tenacious antagonists, a man whose brutal tactics in pursuit of a plan to establish an Islamic state in the Middle East made him the most wanted man in Iraq.

Zarqawi's organization, al-Qaeda in Iraq, is best known for helping to fuel the insurgency in Iraq. But European and Arab intelligence officials and counterterrorism specialists said he never abandoned his primary goals: to topple the monarchy in his native Jordan and attack Jewish targets in Israel and around the world.

As Zarqawi became more prominent in recent years, he expanded his original sphere of influence in the Middle East by forming cells in Europe. Skeptics say that the U.S. government had transformed Zarqawi into a larger-than-life figure by exaggerating his capabilities and using him to personify the Iraqi resistance, which has many factions and appears to rely mainly on Iraqi fighters, not foreigners.

But Zarqawi also helped to enhance his own legend by embracing tactics that have generated enormous publicity.

In May 2004, he personally inaugurated a wave of hostage-takings and beheadings in Iraq by decapitating Nicholas Berg, 26, a businessman from Pennsylvania, and posting the videotaped episode on the Internet. Later, he and his followers circulated videos showing the decapitations of two other Americans, Eugene "Jack" Armstrong, 52, a native of Hillsdale, Mich., and Jack Hensley, 48, of Marietta, Ga.

U.S. forces in Iraq bombed or blew up suspected Zarqawi hideouts and safe houses almost every week, but until yesterday they were unable to corral the 39-year-old Jordanian. The United States placed a $25 million bounty on his head, the same reward offered for Osama bin Laden, the head of the worldwide al-Qaeda organization, with which Zarqawi was affiliated.

In April of this year, Zarqawi apparently attempted to rally his followers by appearing in a video firing a machine gun and encouraging Iraqis to fight against the United States. Last week, he issued an audio tape urging Iraq's Sunni Arabs to take up arms against the country's Shiite majority, which he accused of being "snakes" and "traitors."

Zarqawi was barely known outside Jordan until three years ago, when Colin L. Powell, the secretary of state at the time, identified him as a "collaborator and associate" of bin Laden's. In a speech to the United Nations, Powell cited Zarqawi's presence in Baghdad as evidence that Iraq's president, Saddam Hussein, had struck an alliance with al-Qaeda, a claim that became a major part of the Bush administration's argument for going to war.

Zarqawi was also been accused by some European and Arab authorities of orchestrating plots to cause mass casualties throughout Europe and the Middle East, including in Germany, France, Britain, Spain, Morocco, Tunisia, Jordan and Turkey.

But some European intelligence officials said that claims about Zarqawi's reach were overblown. They said lengthy investigations had turned up no evidence that he had a hand in some of the attacks attributed to him, such as bombings in Madrid and Istanbul.

"He's been centrally elevated to such a position that he seemingly has a hand in everything," Magnus Ranstorp, director of the Center for the Study of Terrorism and Political Violence at St. Andrews University in Scotland, said in an interview before Zarqawi's death. "Certainly he's a real figure, but he's a myth-laden figure, and it's difficult to discern where the lines are."